This invention relates to communication networks and, in particular, to a network architecture and corresponding packet header definition used for end-to-end transport through a connectionless packet-based network of multiple services originating at a variety of different types of tributary interfaces.
Metropolitan access networks of the future must be able to carry packetized data traffic in a low-cost and efficient manner while at the same time providing a means for transport of synchronous or plesiochronous leased-line services. These networks must be flexible enough to offer a combination of Open Systems Interconnection (OSI) Layer 1, Layer 2, and Layer 3 services at lower-speed ingress ports at customer premises, and must be able to uplink aggregated data from these lower-speed interfaces to higher-speed uplink ports located at gateways to core transport networks. These networks must provide facility protection by enabling data to be rerouted in the event of failure, either in mesh or bi-directional ring topologies. These networks must offer different service classes based upon the delay, jitter, and reliability requirements of each customer. These networks must also minimize operational cost by simplifying network management, especially provisioning functions.
Traditional connectionless, packetized data networks based on Internet Protocol (IP) routers or Ethernet switches are inherently closer to meeting the above requirements than connection-oriented asynchronous transfer mode (ATM) networks or time-division-multiplexed synchronous optical network (SONET) rings. However, neither type of network is sufficiently flexible to seamlessly transport data of other protocol types, such as synchronous leased lines, or to offer a combination of OSI Layer 1, 2, and 3 services across different ports on a single device. Ethernet as defined in IEEE Standard 802.3-1998 does not have classes of service. Ethernet devices are limited to operation in local area networks (LANs). IP routers do not enable efficient label-based or tag-based lookups at each hop through a network.
Ethernet with a multi-protocol label-switched (MPLS) label stack as defined in the Internet Engineering Task Force (IETF) Internet Draft xe2x80x9cMPLS Label Stack Encodingxe2x80x9d by E. Rosen et al., draft-ietf-mpls-label-encaps-07.txt, incorporated herein by reference in its entirety, provides 8 classes of service and a 20-bit tag that can be used to switch packets via a label-based lookup at each hop through a network. It also provides an 8-bit time-to-live (TTL) field. Label-switched routers (LSRS) capable of performing a combination of IP routing, MPLS label-based lookups, and policy-based wild-card lookups are able to offer a combination of OSI Layer 1, 2, and 3 services across different ports on a single device. The use of MPLS also enables multiple protocol formats encapsulated within Ethernet frames to be carried as interleaved packetized units within the same data stream.
We have taken note of these ideas and built upon them in our architecture for transport of multiple services in connectionless packet-based networks, and in the formulation of the Optical Packet Transport Network (OPTNet) packet format used for data transport in this architecture. (This name is used to refer to the packet format in this specification purely for convenience and is not necessarily the permanent name associated with this packet format.) Part of the OPTNet packet format resembles the Ethernet with MPLS label stack packet format. Other portions of the OPTNet packet format differ to provide additional or different functionality or improved efficiency. Our architecture supports transport of both connectionless packetized data and framed data from synchronous leased lines. In addition, a fundamental premise of our architecture is simplicity in provisioning and management. Our architecture is optimized for OSI Layer 1 and Layer 2 (Virtual LAN, or VLAN) services and for ring topologies, since for these services in a ring it requires no path setup using a label distribution protocol. It supports OSI Layer 1, Layer 2, and Layer 3 services.
An architecture for transport of multiple services in connectionless packet-based networks is described herein, along with the packet format used for data transport in this architecture. The architecture supports transport of both connectionless packetized data and framed data from synchronous leased lines. The architecture supports transparent packetization of incoming DS1 data. The architecture works for mesh architectures but is optimized for OSI Layer 1 (crossconnect) and Layer 2 (Virtual LAN, or VLAN) services and for ring topologies, since for these services in a ring no path setup is required using a label distribution protocol. In addition, it simultaneously supports OSI Layer 1, Layer 2, and Layer 3 services.